This chapter discusses the permissibility of measures taken for the purpose of enforcing the conservation of maritime resources. In the law of the sea, territoriality plays a central role. Each state is primarily competent to establish the environmental policy applicable within its territory. Under WTO law, this could be interpreted as prohibiting states from conditioning imports to the adoption of environmental measures. In practice, a different view has prevailed. WTO members may adopt trade-restrictive measures to ensure the conservation of maritime resources. The criterion for determining the legality of these measures is not whether they affect the territory of other members but whether there is arbitrary or unjustifiable discrimination. Even a measures with strong extraterritorial effects may be lawful if it aims to attain a permissible non-trade objective and if its application is non-discriminatory.